Colas and coffee appear to have some effect on women’s bone density and could lead to osteoporosis. But tea — even the kind with caffeine — and other sodas do not. And men are not affected at all.
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Confused? You’re not alone.
While scientists have gathered data that links consumption of colas and coffee with loss of bone density, researchers are still looking for the reason why, says rheumatologist Johnny Su, MD.
“Whether there is a causal relationship, and what the exact mechanism of that relationship is, is unclear,” Dr. Su says. “While several studies have shown those relationships, the data overall are not entirely conclusive.”
One reason drinking cola or coffee could impact bone density is that drinking more of these beverages means you’re drinking less beverages like milk, which do promote bone health, Dr. Su says.
Another reason could be that the phosphoric acid in cola leaches calcium out of the bone. Supporting this line of thought is that sodas such as lemon-lime drinks or ginger ale, which are not linked to osteoporosis, lack phosphoric acid.
But, Dr. Su points out, doctors do not recommend cutting back on other foods with high levels of phosphoric acid, like chicken and certain cheeses.
Lastly, it might be caffeine intake that might lead to lower bone density in women. Supporting this theory is that colas — which contain caffeine — and coffee are linked to osteoporosis, while ginger ale and lemon-lime sodas are not. That, however, could be explained by the non-cola drinks’ lack of phosphoric acid.
Further confounding the caffeine theory is that black tea, which contains caffeine, does not impact bone density, Dr. Su says.
Everything in moderation
So while it’s not entirely clear if caffeine consumption lessens bone density, physicians agree in general that excessive amounts of caffeine may have a negative impact, Dr. Su says.
“If you drink those beverages in low amounts — less than 400 milligrams — that’s probably OK,” Dr. Su says. “That means less than four cups of coffee per day might be fine, and less than two cans of cola a day. But if you can cut these beverages out altogether, that’s even better.”
If you still want to drink carbonated beverages, one alternative could be switching to non-caffeinated beverages, Dr. Su says.
A lifetime of weight-bearing exercise and consuming adequate amounts of calcium and vitamin D are the best protection against brittle bones and the health risks associated with osteoporosis, Dr. Su says.
Dairy products, such as non-fat milk and yogurt, are naturally high in calcium, as are vegetables such as kale and broccoli. Also, some foods and beverages, such as orange juice and cereal, are enriched with calcium.